Strawberry plant called &#34;Carlsbad&#34;

ABSTRACT

`Carlsbad` is a short-day (June-bearing) cultivar similar to `Chandler` (U.S. Plant Pat. No. 5,262) but with larger total productivity, substantially larger early productivity, larger fruit, firmer fruit, and is a more vigorous plant.

DESCRIPTION

This invention relates to a new and distinctive short-day type cultivar designated as `Carlsbad`, which resulted from a cross performed in 1988 between the cultivar `Irvine` (U.S. Plant Pat. No. 7,172) and advanced selection Cal 85.218-605.

`Carlsbad` was first fruited at the University of California South Coast Research and Extension Center, near Irvine, Calif. in 1989, where it was selected, originally designated Cal 88.70-613, and propagated asexually by runners. Asexual propagules from this original source have been tested at the South Coast Research and Extension Center, the Watsonville Strawberry Research Facility, and to a limited extent in grower fields starting in 1990.

FIG. 1 shows the general flowering and fruiting characteristics of the plant;

FIG. 2 shows a typical mature leaf during late spring; and

FIG. 3 shows representative mid-season fruit.

`Carlsbad` is typical of short-day types and products fruit over an extended period when treated appropriately in arid, subtropical climates. `Carlsbad` differs from `Irvine` in that `Irvine` is a day-neutral type with essentially no photoperiodic flowering response and as compared with `Carlsbad` is more difficult to grow. The production pattern for `Carlsbad` is similar to that for `Chandler`, although it produces substantially greater quantities of early-season fruit. `Carlsbad` will be of special interest for winter plantings, where `Chandler` has been successful, and in summer plantings where `Pajaro` has been successful.

Plants and foliage: Fruiting plants of `Carlsbad` are larger, more erect, and more vigorous than plants of `Chandler` (U.S. Plant Pat. No. 5,262), and are generally similar in form to plants of `Oso Grande` (U.S. Plant Pat. No. 6,578). `Carlsbad` forms branch crowns in greater quantity than `Chandler` with similar branching to `Oso Grande`. When propagated in the nursery, `Carlsbad` has similar or greater runner production capacity compared with `Chandler`. Comparative statistics for foliar characters, including leaf color, near mid-season are given for the three cultivars in Table 1 with visual comparisons of leaf color according to the Munsell color scale (Nickerson Color Fan) given in Table 5. Leaf color is distinctly lighter on the underside for `Carlsbad`; the differential is larger than for `Chandler` and similar to that for `Oso Grande`. Individual leaflets for `Carlsbad` are larger and somewhat more elongated than `Chandler`, and are less rounded than for `Oso Grande`. Leaves (including petioles) are longer and much broader than for `Chandler`. Petioles are thicker and stiffer than those of `Chandler` and are similar to those of `Oso Grande`. Paired stipules, borne in a median position on the petiole, appear as small, stalked, ovate to heart-shaped structures on most leaves for `Carlsbad` and the comparison cultivars. Stipule size varies greatly both within and among individual plants for `Carlsbad`, and one or both stipules may be absent or may be abscise as the leaf matures. Leaf and petiole pubescence characters for `Carlsbad` are similar to those for `Oso Grande`, except that tomentum on leaves are less dense. Also, leaves for `Carlsbad` are darker than leaves of `Chandler` and similar in color but slightly darker than those of `Oso Grande`. Visual comparisons of fruit color according to the Munsel color scale (Nickerson Color Fan) are given in Table 5. `Carlsbad` has flat (occasionally concave) leaves, which are easily distinguished from ` Chandler`, and are similar in convexity to `Oso Grande`.

Isozymes in leaf extracts: `Carlsbad` has been classified for three isozyme systems using starch gel electrophoresis (Table 2): Phosophoglucoisomerase (PGI), Leucine Aminopeptidase (LAP), and Phosphoglucomutase (PGM). It is distinguishable from all other short-day cultivars released to date. For electrophoretic procedures see: J. Amer. Soc. Hort. Sci. 106:684-687.

Disease and pest reaction: `Carlsbad` is moderately resistant to common leaf spot (Ramularia tulasnei) and powdery mildew (Sphaerotheca macularis). When treated properly, it has equal or greater tolerance to two-spotted spidermites (Tetranychus urticae) than `Chandler`. `Carlsbad` is tolerant to strawberry viruses encountered in California.

                  TABLE 1                                                          ______________________________________                                         Foliar characteristics for                                                     `Carlsbad`, `Chandler`, and `Oso Grande`.                                                Cultivar                                                             Foliar Character                                                                           `Carlsbad` `Chandler` `Oso Grande`                                 ______________________________________                                         Mid-tier leaflet                                                               Length (mm)                                                                    mean        90.4       82.4       77.2                                         range       85-97      78-94      75-80                                        Width (mm)                                                                     mean        75.8       71.4       67.6                                         range       65-82      63-88      62-71                                        Mid-tier leaf                                                                  Length (mm)                                                                    mean        261.0      244.2      191.6                                        range       257-269    218-262    170-200                                      Width (mm)                                                                     mean        162.4      148.0      137.2                                        range       148-175    132-158    130-149                                      Leaf color                                                                     (CIELAB)*                                                                      L*                                                                             mean        30.0       31.4       31.9                                         range       27.7-31.8  27.1-33.3  29.9-33.0                                    a*                                                                             mean        -6.7       -8.0       -5.3                                         range       -3.8--8.8  -5.2--8.2  -4.2--8.3                                    b*                                                                             mean        14.2       16.0       15.5                                         range       10.0-17.5  12.9-21.4  12.5-20.6                                    # leaflets/leaf                                                                            3          3          3                                            Leaf convexity                                                                             flat/slight                                                                               concave    concave                                                  concave                                                            Serrations                                                                     number      few        many       moderate                                     shape       semi-round semi-pointed                                                                              semi-round                                   Leaf pubescence                                                                            moderate   moderate/  moderate/                                                           sparse     heavy                                        Petiole pubescence                                                             density     heavy      heavy      heavy                                        direction   perpendicular                                                                             acropetal  perpendicular                                ______________________________________                                          *CIELAB is the abbreviation of the international color system known as         "Commission Internationale De L'Eclairage" 1978. Recommendations on            uniform color spaces -- color difference equations, psychometric color         terms, Supplement No. 2 to CIE Publication No. 15. PARIS. 2              

                  TABLE 2                                                          ______________________________________                                         Isozyme phenotypes for `Carlsbad`, `Chandler`, and `Oso Grande`.               Cultivar                                                                       Locus   `Carlsbad`   `Chandler`                                                                               `Oso Grande`                                    ______________________________________                                         PGI     A2           A1        A2                                              LAP     B3           B3        B3                                              PGM     C1           C1        C2                                              ______________________________________                                    

Flowering, fruiting, fruit, and production characteristics: Comparative statistics for flower and fruit characters, including fruit color, near mid-season are given for `Carlsbad`, `Chandler` and `Oso Grande` in Table 3. The primary flowers for `Carlsbad` are slightly larger than those of `Chandler` and `Oso Grande`, whereas the sepals are substantially larger than for the comparison cultivars. Each primary flower has 5-7 petals. The calyx for `Carlsbad` is usually even with the shoulder of the fruit, but is occasionally slightly indented and ocassionally necked. The primary fruit shape for `Carlsbad` is a very flat conic, with secondary fruit usually a blocky conic. External fruit color for `Carlsbad`, is lighter than `Chandler`, and `Oso Grande`. and the fruit somewhat less glossy than `Chandler`; internal color is lighter than `Chandler` and darker than for `Oso Grande`. Achenes vary from yellow to dark red, and are even with the fruit surface or slightly extruded.

`Carlsbad` has been tested under a variety of cultural regimes, and optimal performance is obtained when nursery treatments, pre-plant chilling regimes, plant densities, and nutritional programs similar to those that optimize performance for `Chandler` are used. In general, `Carlsbad` is more adapted to early-season planting with less supplemental chilling than `Chandler`.

When treated with appropriate planting regimes, `Carlsbad` has larger fruit and produces greater yields than `Chandler` or `Oso Grande` (Table 4). `Carlsbad` is similar to `Chandler` and `Oso Grande` in its production pattern, although it produces substantially more early-season fruit than either cultivar (with conventional winter planting). Commercial appearance ratings have been comparable to or better than those for `Chandler`. Fruit of `Carlsbad` is firmer than that for `Chandler`; `Carlsbad` is about as firm as `Oso Grande`. Subjectively, `Carlsbad` has very good flavor, somewhat less aromatic than `Chandler`, but with better acid balance and more aromatic components than `Oso Grande`. The fruit will be outstanding for both fresh market and processing, due to its firm flesh and relatively dark internal color, and will be useful for home garden purposes.

                  TABLE 3                                                          ______________________________________                                         Flower and fruit characters for                                                `Carlsbad`, `Chandler`, and `Oso Grande`.                                                  Cultivar                                                           Character     `Carlsbad`                                                                               `Chandler`                                                                               `Oso Grande`                                 ______________________________________                                         # petals                                                                       mean           6.2       6.6       5.0                                         range         5-7       6-8       5-5                                          Flower position                                                                              exposed   even/     exposed                                      (relative to foliage)   exposed                                                Calyx diam. (mm)                                                               mean          63.8      47.7      34.1                                         range         56-70     45-53     27-38                                        Corolla diam. (mm)                                                             mean          40.7      39.3      32.2                                         range         37-44     36-46     27-41                                        Fruit shape                                                                    length/width   1.02      1.33      1.06                                        ratio                                                                          subjective    flat/conic                                                                               flat conic                                                                               blocky/conic                                 Calyx position                                                                               even/slight                                                                              even/slight                                                                              even/slight                                                indent    neck      indent                                       Seed position slight    even/slight                                                                              even                                                       extrude   indent                                                 Fruit color (CIELAB)                                                           external                                                                       L*            25.4      23.6      22.4                                         a*            29.9      38.5      31.2                                         b*            16.3      14.8      17.2                                         internal                                                                       L*            47.8      46.2      54.1                                         a*            37.9      39.1      30.4                                         b*            28.9      29.4      22.7                                         ______________________________________                                    

                  TABLE 4                                                          ______________________________________                                         Performance for selection `Carlsbad` compared with `Oso Grande`                and `Chandler` at the South Coast Research and Extension Center                in 1991. All plants were dug from the South Coast nursery on                   October 1 and planted October 2 (68"/4-row beds, 23,061                        plants/A, 100 g/plant = 425 Crates/A).                                                  Yield    Total           Appear-                                               To 4/1   Yield    Size   ance   Firm-                                          (g/plant)                                                                               (g/plant)                                                                               (g/fruit)                                                                             Score  ness                                  ______________________________________                                         `Carlsbad`                                                                              510      2,308    27.2   4.2    4.7                                   `Chandler`                                                                              463      1,738    23.3   3.9    4.0                                   `Oso Grande`                                                                            530      1,675    25.0   3.8    4.9                                   ______________________________________                                    

                  TABLE 5                                                          ______________________________________                                         Munsell color classification for leaf and fruit characters.                    Munsell                  Munsell                                               Leaf Color Classes       Fruit Color Classes                                          Upper      Lower                                                        Item   (Adaxial)  (Abaxial)  External                                                                               Internal                                  ______________________________________                                         Chandler                                                                              5GY 4/3    5GY 5/6    5R 5/13 7R 5/13                                          5GY 5/6               5R 4/12                                           Oso    5GY 4/3    5GY 5/6    5R 5/13 7.5R 7/9                                         5GY 3/2    7.5GY 6/8  7.5R 5/13                                                                              7.5R 6/12                                 Carlsbad                                                                              7.5GY 4/4  7.5GY 5/8  7.5R 5/13                                                                              7.5R 6/12                                        5GY 4/3    7.5GY 4/7  7.5R 4/11                                                                              7.5R 5/13                                 ______________________________________                                     

We claim:
 1. The new and distinct variety of strawberry plant illustrated and described and having the characteristics above enumerated. 